<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>04_JS流程控制</title>
</head>
<body>
<script>
    //1.顺序结构
    console.log('1');
    console.log('2');
    console.log('3');
    //2.分支结构
    let uname = '';
    if (!uname) {
        //alert('请先登录!');
    } else {
        //alert('欢迎回归!'+uname);
    }
    //3.选择分支
    let gender = 10;
    switch (gender) {
        case 1:
            console.log('男');
            break;
        case 0:
            console.log('女');
            break;
        default:
            console.log('未知');
    }
    //4.循环结构
    let names = ['张三', '李四', '王五'];
    for (var i = 0; i < names.length; i++) {
        console.log(names[i]);
    }
    //如果用var定义循环变量i,循环结束后在此处仍能打印出i的值
    //但如果用let定义,就会报错,变量i不存在!
    console.log(i);

    //5.增强for循环
    //n为每轮循环遍历到的值 names为被遍历的数组
    for(let n of names){
        console .log(n);
    }


</script>
</body>
</html>